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2013 Pro RMK 800 Basic Engine Mods

T
Aug 22, 2017
6
1
3
Newman Lake, WA
Hi all. New to the forum here.

I just bought a bone stock 2013 Pro RMK 800. I want to do a few basic mods to tailor it to my style and preferences (plus, I can't leave anything alone...).

Engine mods planned are pretty basic. I'm planning on a fix kit (not sure which package...open to suggestions), a set of MDS 13.1:1 heads, and a SPI carbon fiber can. The sled only has about 600 miles on it, so I'm not super worried about the top end just yet, but I will probably go ahead and "kit" it and do the mods before the snow flies.

As far as the rest of the sled, there's a ton of good info on here, but I was hoping some first-hand suggestions and recommendations. I ride in NE Washington/North Idaho/NE Oregon neck of the woods, roughly 2200' at the absolute minimum (home), but mostly from, say, 4-7K most of the time, but up to 8-9K at times. I prefer boondocking and tree riding to straight-line hillclimbing, but do quite a bit of both.

Thanks for the help, and great forum!
 

diamonddave

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A Transmission Guy eh? I retired early from the industry after 22 years.

Go with the Fix Kit from MTNTK. Do not waste your time with anything else. I've installed about 25 of these kits with that same head and other's and they work great for our riding altitude, area's. They run way better than a stock set.

I do recommend having the injectors flow tested while you're out. Dr. Injector or Witch Hunter. Injector placement in these motors lends to incredible build up of carbon deposits prematurely. And '13's are the leanest map of all Pro's.

I recommend running the stock can. They're only 12lbs and run well.

IndyDan has a new honing procedure that looks very inviting. He says either use this or use nothing. Ring wear is an issue with this motor.
 
T
Aug 22, 2017
6
1
3
Newman Lake, WA
A Transmission Guy eh? I retired early from the industry after 22 years.

Go with the Fix Kit from MTNTK. Do not waste your time with anything else. I've installed about 25 of these kits with that same head and other's and they work great for our riding altitude, area's. They run way better than a stock set.

I do recommend having the injectors flow tested while you're out. Dr. Injector or Witch Hunter. Injector placement in these motors lends to incredible build up of carbon deposits prematurely. And '13's are the leanest map of all Pro's.

I recommend running the stock can. They're only 12lbs and run well.

IndyDan has a new honing procedure that looks very inviting. He says either use this or use nothing. Ring wear is an issue with this motor.

Thanks for the advice! Like I said, I've been out of the game for quite a while, and I appreciate it.

Yes, I've been building transmissions for 30 years or so now. But mostly Dodge and Ford diesel automatics these days. They're my real bread and butter builds...hundreds of them. It's a living...!

Is it worth the extra money to get the lightweight piston Fix Kit? A hundred extra bucks. Worth it...?
 
I do recommend having the injectors flow tested while you're out. Dr. Injector or Witch Hunter. Injector placement in these motors lends to incredible build up of carbon deposits prematurely.
Dave do you have a link to those injector places? Or do Polaris dealers do testing and servicing on injectors .
 

kiliki

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Dec 27, 2008
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the other two mountain manufactures don't require you to add a "fix kit" to make their sleds run as advertised. so why would you take a know flawed setup over a proven other?
 

tuneman

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the other two mountain manufactures don't require you to add a "fix kit" to make their sleds run as advertised. so why would you take a know flawed setup over a proven other?
It's not as much of a flaw as the internet let's on. In fact, I've seen significantly more broken down Doos and Cats out west than Poo. And, where I ride, there are significantly more Polaris than the others. That's my personal experience, anyway. Not what I read on the internet...
 

kiliki

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It's not as much of a flaw as the internet let's on. In fact, I've seen significantly more broken down Doos and Cats out west than Poo. And, where I ride, there are significantly more Polaris than the others. That's my personal experience, anyway. Not what I read on the internet...

glad you make it out west a few times poor bastage.
When i ride the great lakes i see more broken down poos than cats and doos......LMFAO.

a few of the fix kits are using cat HO pistons to fix it. JFYI. I have installed a few...
 
Last edited:

LoudHandle

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the other two mountain manufactures don't require you to add a "fix kit" to make their sleds run as advertised. so why would you take a know flawed setup over a proven other?

It's far easier to fix an engine (If one feels the need?) than fix all the chassis flaws of the other three manufactures.
 

diamonddave

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Wokeville, WA.
I do recommend having the injectors flow tested while you're out. Dr. Injector or Witch Hunter. Injector placement in these motors lends to incredible build up of carbon deposits prematurely.
Dave do you have a link to those injector places? Or do Polaris dealers do testing and servicing on injectors .

I do use the kit with the lighter pistons

Mountainhorse used to have a link for Witchunter. I just take mine into Dr. Injector as they are local.

Polaris does not have this ability.

Found there's.

http://www.witchhunter.com/
 

wildcard28

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Dec 18, 2007
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Clarkston WA
s375.photobucket.com
Good thread, I'm also a Transmission guy myself, been building tramsmission for 32yrs now had my own Shop for 12yrs been working for a god shop for 6yrs since I closed mine work here home town Clarkston Wa / Lewiston Id, my dad opened his first shop 2yrs before I was born (1967) and worked for him off and on for 14yrs, best teacher to have. like you mention seems to me dodge 48re, 68rfe, ford 4r100, 5r110 are the norm course Tons of 4l60e`s 3-4 clutch failure almost everyone huh, Lol.

Fun trade, think I'm gonnna put the same fix it kit and head on my sled that diamond dave recommended, my engine doesn't have much over 400miles its 14 motor in 12 chassis, fun sled

Wildcard
 
T
Aug 22, 2017
6
1
3
Newman Lake, WA
like you mention seems to me dodge 48re, 68rfe, ford 4r100, 5r110 are the norm course Tons of 4l60e`s 3-4 clutch failure almost everyone huh, Lol.

I own and operate my shop here in the Spokane area. My main market is the Dodge 47RE/48RE's these days. I build and ship them all over the western US, and ship valve bodies all over the US and Canada. I have some pressure control mods and shift calibrations of my own design that work extremely well, and solves the lack of pressure that plagues these things behind the Cummins. Things a "shift kit" won't address.

As far as local work, it's a steady diet of 47RE/48RE's, a boat load of 4R100's, quite a few 5R110's, and the occasional Allison thrown in for good measure. I still build the occasional 4L60E/4L80E when I can't talk my way out of it. After literally building thousands of those things, I just can't bring myself to get excited about building them. Twice the work for 1/2 the money...
 

Murph

Polaris Moderator/ Polaris Ambassador/ Klim Amb.
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Transdoc— welcome to the Forum and welcome back to sledding.


As Dave suggested, the Indy Specialty honing process has proven to increase ring life and top end interval significantly. They can also flow / spray pattern test your injectors.
 
T
Aug 22, 2017
6
1
3
Newman Lake, WA
Transdoc— welcome to the Forum and welcome back to sledding.


As Dave suggested, the Indy Specialty honing process has proven to increase ring life and top end interval significantly. They can also flow / spray pattern test your injectors.

Thanks! I appreciate the help and the welcome. We rode most of last season, and the family absolutely loved it! Looking forward to some longer trips this year!
 

SayatodaU.P.eh?

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Mar 23, 2008
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Michigan
Good honing and factory pistons is all you need. At that mileage, I wouldn't touch the engine.

Brand new Polaris injectors are not much more than what you would have into having Indy Dan clean them. I WOULD have him, or someone, machine, shim and balance your primary clutch.
 

LoudHandle

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Emphasis on “GOOD” honing, like sent to Indy Dan, anything less will be a detriment to piston / ring life! Even the factory hone finish is quite sub-standard in comparison. Nothing you have at home in the garage or even most professional machine shops will make a suitable surface finish. Ball Hones and even rigid stone hones (even the ones sold as “for Nicasil” will just tear up the surface and accelerate piston and ring failure.

That said, do whatever makes you feel good.
 

gtwitch

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Read and pay attention to what Indy Dan says about honing!!!! There is a great thread here on sno west by Indy Dan (8 pages or so). I did this back 3 or so years ago and have not honed one since if the cylinder looks OK and has no major flaws or scratches. Light cleanup with scotch-brite and wash with soap and warm water and mic it and check clearances. If you want to use durability (fix kit plate) then use Arctic Cat replacement 800 pistons either Sno X or SPI---I have had good luck here. If you do not want to use durability kit spacer plate-- just use either Polaris MY 15 stock pistons or SPI direct replacement pistons. Again, do not hone if Cyl is good, ring end gap at .020, skirt clearance .004 to .005, lub well with 2 cycle oil as you are going back together with new pin bearings. Break in properly and go to the mountain!!
gtwitch in wyoming
 
S
Mar 6, 2008
510
346
63
Northern Sweden
I have Fire'N Ice Torque arm/torque stop on both PTO and MAG sides and I have not changed a single belt since I put them in.
Got about 1000km on my first belt and put the Fire'N Ice stuff in just about when I changed belt and the "new" belt is past 3000km now and counting.
 
S
Feb 21, 2009
810
91
28
56
2012

Had a cylinder shirt fail which seized motor put on indy dan heads and oem pistons and thing is bomber and runs hard. JMO
 
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